Textiles natural cellulose fibers: cotton

It was later determined that the crystallographic form cellulose I was irreversibly chang to the form cellulose II. The unit cell of cellulose II also contained two cellobiose units with axes a = 0.814 nm, b = 1.03 nm, c = 0.914 nm, and fi = 62° (angle between a and c axes). The fibrillar cellulose II is less ordered than fibrillar cellulose I and is about 60% crystalline. This 1840s development, now called mercerization, is probably the most important process for the modification of natural cellulose, particularly cotton cellulosic textile fibers, to current date. Lowe later confirmed these results and showed the effects of mercerization on cotton fibers while under tension. 

An older method of cellulose fiber modification is mercerization [22,33-36], which has been widely used on cotton textiles. Mercerization is an alkali treatment of cellulose fibers. It depends on the type and concentration of the alkalic solution, its temperature, time of treatment, tension of the material, and the additives used [33,36]. At present there is a tendency to use mercerization for natural fibers as well. Optimal conditions of mercerization ensure the improvement of the tensile properties [33-35,37] and absorption characteristics [33-35], which are important in the composing process. 

Uses/Sources. Wood contains 50-70% cellulose cotton and other textile fibers of plant origin contain 65-95% rayon is prepared by dissolving natural cellulose and then precipitating it from solution, with some loss of crystallinity. Cellulose is made into cellophane film and is used to form fibers, resins, coatings and gums. 

The natural fibers obtained from cotton, wood, flax, hemp, and jute all are cellulose fibers and serve as raw materials for the textile and paper industries. In addition to its use as a natural fiber and in those industries that depend on wood as a construction material, cellulose is used to make cellulose acetate (for making rayon acetate yarn, photographic film, and cellulose acetate butyrate plastics), nitric acid esters (gun cotton and celluloid7), and cellulose xanthate (for making viscose rayon fibers). The process by which viscose rayon is manufactured involves converting wood pulp or cotton Iinters into cellulose xanthate by reaction with carbon disulfide and sodium hydroxide ... 

The development of methods and tests for preserving natural textile fibers is surveyed. The effect of the environment in which the textiles are stored or exposed, chemical, physical, and biological agents responsible for their degradation, and test methods for evaluating their performance and extent of damage are discussed. Emphasis is on cotton, wool, and silk, with selected references on other cellulosic fibers such as jute and linen. 

Camille and Henry Dreyfus developed the first commercial process to manufacture cellulose acetate in 1905 and commercialized the spinning of cellulose acetate fibers in 1924 in the United States. At that time, the only other human-made fiber was viscose rayon, which was still in its early stages of commercialization. The main textile fibers were natural fibers cotton, wool, silk, and flax. Cellulose triacetate textile fiber was commercialized later in the 1950s. The tremendous technical effort by the Dreyfus Brothers resulted in more than 300 patents describing such significant inventions as the dry-spinning process and disperse dyeing. 

Fiber production is a large-volume business around 60 million metric tons per year. About 40% of this is natural fiber cotton and wool the remaining part is man-made , synthetic fiber polyester, polyamide, cellulose, acrylics, and so forth. More than 90% is applied in textiles or carpets. Only about 5% is used in industrial applications. And the new, advanced , high-modulus fibers Technically and commercially very interesting, but we are talking of no more than about 0.2% of the fiber capacity ... 

Textile fibers are normally broken down into two main classes, natural and man-made fibers. All fibers which come from natural sources (animals, plants, etc.) and do not require fiber formation or reformation are classed as natural fibers. Natural fibers include the protein fibers such as wool and silk, the cellulose fibers such as cotton and linen, and the mineral fiber asbestos. Man-made fibers are fibers in which either the basic chemical units have been formed by chemical synthesis followed by fiber formation or the polymers from natural sources have been dissolved and regenerated after passage through a spinneret to form fibers. Those fibers made by chemical synthesis are often called synthetic fibers, while fibers regenerated from natural polymer sources are called regenerated fibers or natural polymer fibers. In other words, all synthetic fibers and regener-... 

Cellulose is present in all plants and algae cellulose of the tunicin type forms a shell of certain marine creatures, and it is also synthesized by some microorganisms. The main sources of cellulose are plants. The content of cellulose in herbaceous plants is 30-40%, in woods 45-50%, in bast plants (flax, ramie, etc.) 60-70%, and in cotton fibers upwards of 90% (Young et al., 1986). The cellulose is an inexhaustible natural source of raw materials for production of textile, paper, cardboard, fibers, films, fillers. 

Mention has already been made of two polymers that can be obtained naturally from living animals silk (from the silkworm) and wool (from sheep). They are proteins made of various amino acids both are used in textiles. Other biologically derived polymers are also familiar such as wood, starch, and some sugars. We will not cover these in detail here. However, certain cellulosics we will discuss briefly since they are compared to synthetic fibers later. Cellulose is the primary substance of which the walls of vegetable cells are constructed and is largely composed of glucose residues. It may be obtained from wood or derived in very high purity from cotton fibers, which are about 92% pure cellulose. 

Until the 20th century mankind was limited to natural fibers such as wool, cotton, linen, and for the rich, silk. The first man-made fiber was artificial silk rayon (1910), which was based on cellulose. The big jump came with the invention of nylon by Wallace Carothers, with commercial production starting in 1939, followed in the 1950s by acrylics (which, when mixed with cotton, produced the wash-and wear textiles), polyesters, and many others. 

Cotton (Figure 1.1) is the most important natural textile fiber, as well as cellulosic textile fiber, in the world, used to produce apparel, home furnishings, and industrial products. Worldwide about 40% of the fiber consumed in 2004 was cotton [1]. (See also Table 9.1 World Production of Textile Fibers on page 130.) Cotton is grown mostly for fiber but it is also a food crop (cottonseed)—the major end uses for cottonseeds are vegetable oil for human consumption whole seed, meal, and hulls for animal feed and linters for batting and chemical cellulose. 

---